<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>

</head>
<body>
</body>
<script>
   var circle={R:4,mianji:function () {
           return 3.14*this.R*this.R;
       },zhouchang:function () {
           return 2*3.14*this.R;
       }};
   alert(circle.mianji());
</script>
</html>